Magnetic Resonance Neurography of the Foot and Ankle.

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation.

Anatomical principles of ankle denervation - An update.

BACKGROUND: Denervation is a surgical option in ankle arthrosis when conservative therapy has failed. Sectioning all joint branches is essential for its success. The locations of the articular branches of the saphenous (Sa), tibial (Ti), sural (Su), superficial (Ps) and deep peroneal (Pp) nerves are specified. METHODS: In 16 cryopreserved specimens, the courses of the nerves were prepared. Their articular branches were identified, and their respective locations documented by using a new reference system. RESULTS: The articular branches to the ankle ranged from 5 to 30 cm measured from the foot sole. The Sa should be transected at 22.5 cm, the Su at 20 cm, and the Pp at 15 cm. The Ti should be skeletonized up to 25 cm. Epifascial dissection of the Ps is to be performed below 15 cm. CONCLUSION: The study specifies the joint branches of the ankle in an intraoperatively reproducible reference system and thus minimizes the required skin incisions.

Sural nerve: imaging anatomy and pathology.

High resolution ultrasound (US) and magnetic resonance (MR) neurography are both imaging modalities that are commonly used for assessing peripheral nerves including the sural nerve (SN). The SN is a cutaneous sensory nerve which innervates the lateral ankle and foot to the base of the fifth metatarsal. It is formed by contributing nerves from the tibial and common peroneal nerves with six patterns and multiple subtypes described in literature. In addition to the SN being a cutaneous sensory nerve, the superficial location enables the nerve to be easily biopsied and harvested for a nerve graft, as well as increasing the susceptibility to traumatic injury. As with any peripheral nerves, pathologies such as peripheral nerve sheath tumors and neuropathies can also affect the SN. By utilizing a high frequency probe in US and high-resolution MR neurography, the SN can be easily identified even with the multiple variations given the standard distal course. US and MRI are also useful in determining pathology of the SN given the specific image findings that are seen with peripheral nerves. In this review, we evaluate the normal imaging anatomy of the SN and discuss common pathologies identified on imaging.

"High ankle block" for surgery at the ankle joint.

BACKGROUND: Surgery around the ankle is increasingly embedded in outpatient treatment concepts. Unfortunately, the classic "ankle block" as a concept of regional anesthesia is inappropriate for surgery around the ankle because the injection sites are too distal to block this specific region. METHODS: The "high ankle block" avoids this disadvantage by dislocating the injection points 15 cm proximal to the malleoli. Three of five peripheral nerves necessary to perform the block can be reached by a circumferential subcutaneous wall. The Posterior Tibial Nerve and the Deep Peroneal Nerve are addressed by an ultrasound guided approach. RESULTS: The efficacy of the technique is highlighted by a case series (3 cases) in which the new blockade was used as a stand-alone procedure, i.e. without additional general anesthesia. CONCLUSIONS: The "high ankle block" may serve as an ultrasound guided expansion to the classic techniques, extending the operative spectrum to the ankle region.

Complications Associated with Peripheral Nerve Blocks.

Outpatient orthopedic surgery is gradually becoming the standard across the country, as it has been found to significantly lower costs without compromising patient care. Peripheral nerve blocks (PNBs) are largely what have made this transition possible by providing patients excellent pain control in the immediate postoperative period. However, with the increasing use of PNBs, it is important to recognize that they are not without complications. Although rare, these complications can cause patients a significant amount of morbidity. It is important for surgeons to know the risks of peripheral nerve blocks and to inform their patients.

Ultrasound-Guided Proximal and Distal Tarsal Decompression: An Analysis of Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels.

Objectives. To analyze the reliability of measurements of tarsal tunnel and medial and lateral plantar tunnel pressures before and after ultrasound-guided release. Measurements taken were guided by ultrasound to improve reliability. This novel approach may help surgeons make surgical decisions. The second objective was to confirm that decompression using ultrasound-guided surgery as previously described by the authors is technically effective, reducing pressure to the tarsal and medial and lateral plantar tunnels. Methods. The study included 23 patients with symptoms compatible with idiopathic tarsal tunnel syndrome (TTS). The first step was to measure intracompartmental pressure of the tarsal tunnel, medial plantar tunnel, and lateral plantar tunnel preoperatively. The second step was ultrasound-guided decompression of the tibial nerve and its branches. Subsequently, pressure was measured again immediately after decompression in the 3 tunnels. Results. After surgery, the mean values significantly dropped to normal values. This represents a validation of effective decompression of the tibial nerve and its branches in TTS with ultra-minimally invasive surgery. Conclusions. The ultrasound-guided surgical technique to release the tibial nerve and its branches is effective, significantly reducing pressure in the tunnels and, thereby, decompressing the nerves.Level of evidence: Level IV.

The relationship of the Phantom® Lapidus Intramedullary Nail System to neurologic and tendinous structures in the foot: An anatomic study.

BACKGROUND: The purpose of our cadaveric study was to determine the proximity of nail insertion and interlocking mechanisms in the Phantom® Lapidus Intramedullary Nail System to neurologic and tendinous structures in the foot. METHODS: We used 10 fresh-frozen human lower-extremity specimen cadavers. For each specimen, the Nail System was inserted as described in the published technique guide. We then performed dissection on the tibialis anterior tendon, extensor hallucis longus tendon, and medial dorsal cutaneous branch of the superficial peroneal nerve and we measured and averaged the distances from each of these structures from the nail. RESULTS: The tibialis anterior tendon was in closest proximity to the insertion of the proximal medial interlock K-wire with an average distance of 0.4mm from the tendon. The extensor hallucis longus tendon was in closest proximity to nail insertion with an average distance of 1.2mm. The medial dorsal cutaneous branch of the superficial peroneal nerve was in closest proximity to the distal interlock K-wire with an average distance of 7.5mm. CONCLUSIONS: The tibialis anterior tendon, extensor hallucis longus tendon, and the medial dorsal cutaneous branch of the superficial peroneal nerve are at risk with the insertion of the nail system. Blunt dissection should be performed using this system with a path to bone before instrumentation to reduce the risk of nerve and tendon injury in the foot.

Lateral popliteal block in foot and ankle surgery: Comparing ultrasound guidance to nerve stimulation. A prospective randomized trial.

BACKGROUND: The popliteal block has several benefits in foot and ankle surgery. It reduces postoperative pain, limits the use of narcotics and facilitates early discharge. The aim of this prospective randomized trial was to evaluate whether ultrasound guidance improves block characteristics compared to the nerve stimulation technique in lateral popliteal blocks. METHODS: Patients were randomized to receive either a lateral popliteal block using neurostimulation or ultrasound guidance. Block performance time, number of needle pricks, number of redirections were recorded. Pain upon admission to and discharge from post anesthesia care unit (PACU) was recorded. Block duration, patient satisfaction, pain at block site and amount of opioids used in PACU and between subsequent followup visits was recorded. Patients were followed for 12 weeks postoperatively. RESULTS: There was no statistically significant difference between the two groups in terms of number of pricks, time for the block to wean, pain upon admission to PACU, amount of opioids received in PACU, pain upon discharge from PACU, pain at the operative site, pain at the block site, toe motor function and toe sensation. There was a statistically significant difference in the block procedure performance time between the two groups, with the control group being faster (P<0.0001). A significantly larger number of patients in the control group required more than three needle redirections (P=0.0060). CONCLUSIONS: The lateral sciatic popliteal block using nerve stimulation had similar block characteristics and patient satisfaction with a significantly faster performance time compared to the ultrasound guided technique. LEVEL OF EVIDENCE: Level I, prospective randomized study.

[Ankle block]. / Fußblock.

OBJECTIVE: The so-called ankle block represents a local anesthesia form which enables easy performance of all surgical procedures of the foot and ankle. INDICATIONS: Interventions distal to the medial and lateral malleoli. CONTRAINDICATIONS: Acute and chronic infections in the area of injection; allergy to the local anesthesia. SURGICAL TECHNIQUE: All five sensory foot nerves are blocked. The two deep lying nerves, the tibial nerve and the deep fibular nerve, can be directly anesthetized perineurally using anatomical landmarks. The other three nerves are subcutaneously infiltrated near their branches. RESULTS: The success rate ranges from 88 to 94%; smaller areas may also be further blocked intraoperatively. The ankle block is a cost-effective procedure which can also be performed without problems in multimorbid patients due to its minor side effects.

Pretreatment of ankle nerve block provides better postoperative analgesia than peri-incisional local anesthetic infiltration in hallux valgus correction surgery.

Adequate postoperative analgesia after hallux valgus (HV) correction surgery improves early mobilization and decreases hospital stay. Peripheral nerve block and peri-incisional local anesthetic (LA) infiltration are both widely used for pain management in orthopedic surgeries. The aim of this study was to compare the analgesic effects between the ankle block and peri-incisional infiltration technique in patients undergoing HV correction surgery. Ninety patients scheduled for hallux valgus correction surgery were randomly allocated into three groups. In group N, patients were pretreated with tibial and peroneal nerve blocks with 8-10 mL of 0.25% bupivacaine before surgery. In group P, patients received the same LA for peri-incisional infiltration preoperatively. In group C, patients underwent surgery without regional analgesic pretreatment. All patients had intravenous fentanyl patient control analgesia as part of multimodal postoperative pain management. Fentanyl consumption, rest and moving pain scale, and adverse effects were evaluated at postoperative 6 h (Poh6), Poh12, Poh 24, and Poh36, respectively. Patients receiving bilateral feet surgeries were excluded in this study. Seventy-five patients were enrolled into final analysis. The patients in group N expressed lower resting and moving pain scores at Poh6, but the pain scores turned similarly among the three groups following Poh12 and then. The total fentanyl consumption was significantly less in group N than in group P. The postoperative activities and mood disturbance were not significantly different between groups after Poh12 and then. We conclude that ankle block is better than peri-incisional LA infiltration in HV correction surgery in pain relief and fentanyl consumption.

Identifying the emergence of the superficial peroneal nerve through deep fascia on ultrasound and by dissection: Implications for regional anesthesia in foot and ankle surgery.

Regional anesthesia relies on a sound understanding of anatomy and the utility of ultrasound in identifying relevant structures. We assessed the ability to identify the point at which the superficial peroneal nerve (SPN) emerges through the deep fascia by ultrasound on 26 volunteers (mean age 27.85 years ± 13.186; equal male: female). This point was identified, characterized in relation to surrounding bony landmarks (lateral malleolus and head of the fibula), and compared to data from 16 formalin-fixed human cadavers (mean age 82.88 years ± 6.964; equal male: female). The SPN was identified bilaterally in all subjects. On ultrasound it was found to pierce the deep fascia of the leg at a point 0.31 (±0.066) of the way along a straight line from the lateral malleolus to the head of the fibula (LM-HF line). This occurred on or anterior to the line in all cases. Dissection of cadavers found this point to be 0.30 (±0.062) along the LM-HF line, with no statistically significant difference between the two groups (U = 764.000; exact two-tailed P = 0.534). It was always on or anterior to the LM-HF line, anterior by 0.74 cm (±0.624) on ultrasound and by 1.51 cm (±0.509) during dissection. This point was significantly further anterior to the LM-HF line in cadavers (U = 257.700, exact two-tailed P < 0.001). Dissection revealed the nerve to divide prior to emergence in 46.88% (n = 15) limbs, which was not identified on ultrasound (although not specifically assessed). Such information can guide clinicians when patient factors (e.g., obesity and peripheral edema) make ultrasound-guided nerve localization more technically challenging. Clin. Anat. 32:390-395, 2019. © 2019 Wiley Periodicals, Inc.

Calcaneal Osteotomy Safe Zone to Prevent Neurological Damage: Fact or Fiction?

BACKGROUND: Calcaneal osteotomy is a commonly used surgical option for the correction of hindfoot malalignment. A previous cadaveric study described a neurological "safe zone" for calcaneal osteotomy. We performed a retrospective chart review to evaluate the presence of neurological injuries following calcaneal osteotomies and the location of the osteotomy in relation to the reported safe zone. METHODS: In this retrospective study, we reviewed charts of patients who underwent calcaneal osteotomy at our institution from 2011 to 2015. All immediate postoperative radiographs were examined and the shortest distance between the calcaneal osteotomy line and a reference line connecting the posterior superior apex of the calcaneal tuberosity to the origin of the plantar fascia was measured. If the osteotomy line was positioned within an area 11.2 mm anterior to the reference line, it was considered to be inside the neurological safe zone. We correlated the positioning of the osteotomy with the presence of postoperative neurological complications. RESULTS: We identified 179 calcaneal osteotomy cases. Of the 174 (97.2%) nerve injury-free cases, 62.6% (109/174) were performed inside the defined "safe zone" while 37.4% (65/174) outside. A total of 5 (2.8%) nerve complications were identified: 3 (60%) were inside the safe zone and 2 (40%) outside the safe zone. Osteotomies outside the safe zone had a 1.114 relative risk of nerve injury with a 95% CI of 0.191 to 6.500 and showed no statistically significant difference ( P = .9042). CONCLUSION: Our findings suggest that the clinical "safe zone" in calcaneal osteotomies may not actually exist, likely because of wide anatomical variation of the implicated nerves, as described in prior studies. Patients should be properly counseled preoperatively on the low, but seemingly fixed, risk of nerve injury before undergoing calcaneal osteotomy. LEVELS OF EVIDENCE: Level III: Retrospective comparative study.

Diffusion Tensor Imaging of the Ankle as a Possible Predictor of Chemotherapy Induced Peripheral Neuropathy: Pilot Study.

PURPOSE: Chemotherapy induced peripheral neuropathy (CIPN) is seen in up to 75% of treated cancer patients and can drastically limit their medical management and affect quality of life. Clinical and electrodiagnostic testing for CIPN have many pitfalls. Magnetic resonance neurography (MRN) is being increasingly used in the evaluation of peripheral nerves. Diffusion tensor imaging (DTI) shows promise in the workup of peripheral nerves. In this prospective pilot study, we investigated a possible relationship between DTI and peripheral neuropathy of the ankle and foot in cancer patients treated with chemotherapy. METHODS: Nine cancer patients with and without CIPN were clinically evaluated using vibratory perception threshold (VPT) testing. VPT score of >25Volts defined presence of CIPN. The posterior tibial nerve and branches in both feet were imaged using MRN and DTI. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured at the posterior tibial, medial plantar, and lateral plantar nerves. Measurements for the CIPN group were compared to without CIPN by VPT cutoff. Correlations and possible relationships between DTI parameters and CIPN were analyzed. RESULTS: A total of 16feet of 9 enrolled patients were imaged (9feet with CIPN and 7feet without CIPN). Average age was 60.6 ± 13.4 years (range: 33-74). Posterior tibial nerve ADC values were significantly lower than the medial plantar nerve ADC values in all feet (F = 3.50, P = 0.04). We found a correlation with FA and ADC values at specific nerve locations with CIPN, with the left medial plantar nerve FA value and left lateral plantar nerve ADC value demonstrating the strongest positive correlations (0.73 and 0.62, respectively). CONCLUSIONS: The use of DTI for assessing CIPN is challenging but promising. This pilot study provides preliminary data showing correlations between FA and ADC measurements with CIPN and potential utility of DTI as a predictive marker of onset and severity of CIPN in the ankle and foot, which could aid in preventive strategies. Larger, prospective DTI studies are needed to draw definitive conclusions. CLINICAL RELEVANCE: MRN with DTI shows promising results as a potential predictive marker of CIPN in the ankle and foot.

The Distribution Pattern of the Neurovascular Structures for Anterior Ankle Arthroscopy to Minimize Structural Injury: Anatomical Study.

INTRODUCTION: The aim of this study was to investigate entry points for anterior ankle arthroscopy that would minimize the risk of neurovascular injury. METHODS: Thirty-eight specimens from 21 Korean cadavers (age range from 43 to 92 years, mean age of 62.3 years) were used for the study. For the measurements, the most prominent points of the lateral malleolus (LM) and the medial malleolus (MM) were identified before dissection. A line connecting the LM and MM, known as the intermalleolar line, was used as a reference line. We measured 14 variables passed on the reference line. RESULTS: This study found that the nerves were located at 40.0%, 50.0%, and 82.0% of the reference line from the lateral malleolus. We also found that the arteries were located at 22.0%, 35.0%, and 60% of the reference line from the lateral malleolus. DISCUSSION: If all the variables are combined (nerves, arteries, and veins), then there is no safety zone for anterior portal placement. Therefore, we recommend that surgeons concentrate primarily on the arteries and nerves in the clinical setting.

Nerve Entrapment in Ankle and Foot: Ultrasound Imaging.

Peripheral nerve entrapment of the ankle and foot is relatively uncommon and often underdiagnosed because electrophysiologic studies may not contribute to the diagnosis. Anatomy of the peripheral nerves is variable and complex, and along with a comprehensive physical examination, a thorough understanding of the applied anatomy is essential. Several studies have helped identify specific areas in which nerves are commonly compressed. Identified secondary causes of nerve compression include previous trauma, osteophytes, ganglion cysts, edema, accessory muscles, tenosynovitis, vascular lesions, and a primary nerve tumor. Imaging plays a key role in identifying primary and secondary causes of nerve entrapment, specifically ultrasound (US) and magnetic resonance imaging. US is a dynamic imaging modality that is cost effective and offers excellent resolution. Symptoms of nerve entrapment may mimic other common foot and ankle conditions such as plantar fasciitis.

Perineural Versus Systemic Dexamethasone in Front-Foot Surgery Under Ankle Block: A Randomized Double-Blind Study.

BACKGROUND AND OBJECTIVES: Among the different adjuvants, dexamethasone is one of the most accepted to prolong the effect of local anesthetics. This study aims to determine the superiority of perineural over systemic dexamethasone administration after a single-shot ankle block in metatarsal osteotomy. METHODS: We performed a prospective, double-blind, randomized study. A total of 100 patients presenting for metatarsal osteotomy with an ankle block were randomized into 2 groups: 30 mL ropivacaine 0.375% + perineural dexamethasone 4 mg (1 mL) + 2.5 mL of systemic saline solution (PNDex group, n = 50) and 30 mL ropivacaine 0.375% + 1 mL of perineural saline solution + intravenous dexamethasone 10 mg (2.5 mL) (IVDex group, n = 50). The primary end point was the duration of analgesia defined as the time between the performance of the ankle block and the first administration of rescue analgesia with tramadol. RESULTS: Time period to first rescue analgesia with tramadol was similar in the IVDex group and the PNDex group. Data are expressed as mean (SD) or median (range). Duration of analgesia was 23.2 (9.5) hours in the IVDex group and 19 (8.2) hours in the PNDex group (P = 0.4). Consumption of tramadol during the first 48 hours was 0 mg (0-150 mg) in the IVDex group versus 0 mg (0-250 mg) in the PNDex group (P = 0.59). Four (8%) and 12 (24%) patients reported nausea or vomiting in the IVDex group and the PNDex group, respectively (P = 0.03). CONCLUSIONS: In front-foot surgery, perineural and systemic administrations of dexamethasone are equivalent for postoperative pain relief when used as an adjuvant to ropivacaine ankle block. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02904538.

Medial Structure Injury During Suture Button Insertion Using the Center-Center Technique for Syndesmotic Stabilization.

BACKGROUND: The center-center technique for syndesmosis fixation has been described as an improved and reliable technique for proper reduction of the syndesmosis during ankle fracture repair. Concurrently, the use of flexible fixation with a suture button is becoming an established means of syndesmosis stabilization. The purpose of this cadaveric study was to assess for medial structure injury during the placement of a suture button using the center-center technique for ankle syndesmosis repair at 3 insertion intervals. METHODS: Simulated open syndesmosis repair was performed on 10 cadaveric specimens. Three intervals were measured at 10 mm, 20 mm, and 30 mm proximal to the level of the distal tibial articular surface along the fibula. Proper longitudinal alignment of the center-center technique was completed under fluoroscopic guidance and was marked on the medial aspect of the tibia. The 3 intervals were drilled in the appropriate technique trajectory. The suture button was subsequently passed through each drill-hole interval. A single observer used a digital caliper to measure the distance from each suture button aperture with respect to the tibialis anterior tendon, tibialis posterior tendon, and greater saphenous vein and nerve. RESULTS: A total of 30 interval measurements (10 cadavers with 3 suture button segments each) were used for data analysis. Direct impingement on the greater saphenous vein was seen in 11 of 30 (36.6%) interval measurements. Six of the 11 (54.5%) observed saphenous structure impingement events occurred at the 10-mm drill hole. CONCLUSION: The results of the present study suggest that the use of the center-center technique for syndesmosis repair with suture button fixation risks preventable injury to the greater saphenous neurovasculature. CLINICAL RELEVANCE: To understand the medial ankle anatomy, as it pertains to insertion of flexible syndesmotic fixation in a cadaveric model, to aid in prevention of clinical iatrogenic injury.

Comparable Postoperative Pain Levels Using 2 Different Nerve Blocks in the Operative Treatment of Displaced Intra-articular Calcaneal Fractures.

BACKGROUND: The aim of this study was to compare the postoperative pain levels in patients undergoing osteosynthesis of the calcaneus with either a popliteal nerve block or an ankle block. METHODS: A retrospective analysis of all consecutive patients undergoing operative fixation of a calcaneal fracture via a sinus tarsi approach between August 2012 and April 2017 in a single foot/ankle specialized center was performed. Single-shot popliteal blocks were placed using ultrasound guidance by an anesthesiologist while ankle blocks were placed by a foot/ankle specialized surgeon. Pain levels were measured through the numerical rating scale (NRS). In total, 83 patients were included in this study; 33 received a popliteal block, and 50 received an ankle block. No statistically significant differences were present in baseline characteristics between the 2 groups. RESULTS: Comparable postoperative pain levels were observed in both groups. There was no statistically significant difference in amount of morphine used between the 2 groups. CONCLUSION: No differences were found in postoperative pain levels between patients receiving a single-shot popliteal block and patients who received a single-shot ankle block following calcaneal fracture surgery. LEVEL OF EVIDENCE: III, comparative series.

Effect of Perineural Dexamethasone on the Duration of Single Injection Saphenous Nerve Block for Analgesia After Major Ankle Surgery: A Randomized, Controlled Study.

BACKGROUND AND OBJECTIVES: Patients undergoing major elective ankle surgery often experience pain from the saphenous nerve territory persisting beyond the duration of a single-injection saphenous nerve block. We hypothesized that perineural dexamethasone as an adjuvant for the saphenous nerve block prolongs the duration of analgesia and postpones as well as reduces opioid-requiring pain. METHODS: Forty patients were included in this prospective, randomized, controlled study. All patients received a continuous sciatic catheter and were randomized to receive a single-injection saphenous nerve block with 10 mL of 0.5% bupivacaine with 1:200,000 epinephrine with addition of 1 mL of saline or 1 mL of 0.4% (ie, 4 mg) dexamethasone. The primary outcome was duration of saphenous nerve block estimated as the time until the first opioid request. Secondary outcomes were opioid consumption and pain. RESULTS: The mean (SD) duration of the saphenous nerve block until first opioid request was 29.4 (8.4) hours in the dexamethasone group and 23.2 (10.3) hours in the control group (P = 0.048). The median opioid consumption [interquartile range] during the first 24 hours was 0 mg [0-0] versus 1.5 mg [0-14.2] in the dexamethasone and control groups, respectively. Nonparametric comparison of opioid consumption from 0 to 24 hours was statistically significant. The opioid consumption was similar in the two groups in the time interval 24 to 48 postoperative hours. CONCLUSION: Perineural dexamethasone as an adjuvant for the single-injection subsartorial saphenous nerve block can prolong analgesia and reduce opioid-requiring pain after major ankle surgery.

Estructuras neurovasculares en riesgo durante abordajes artroscópicos en tobillo: un estudio cadavérico / Neurovascular structures at risk during arthroscopic approaches to the ankle: a cadaveric study

La artroscopía de tobillo ha tenido un aumento en su utilización en las últimas tres décadas para la corrección quirúrgica de afecciones del tobillo. Se prefiere a la cirugía abierta por sus múltiples ventajas, destacando la disminución de las complicaciones, con una prevalencia de 7,3 % para la artroscopia y 15,9 % para la cirugía abierta. Estudios previos de artroscopia de tobillo reportan complicaciones generales entre el 0,9 a 17 %, de las cuales el 33 a 50 % envuelven los nervios cutáneos, principalmente el nervio fibular superficial o alguna de sus ramas. El objetivo del presente estudio fue determinar estructuras neurovasculares en riesgo próximas a los portales artroscópicos del tobillo descritos en la literatura. Se llevó a cabo un estudio anatómico observacional, transversal y descriptivo. La muestra consistió en 10 tobillos de población mexicana en los cuales se introdujeron cánulas artroscópicas en algunos portales de tobillo descritos en la literatura y se realizó una disección superficial de los pies, posteriormente se determinó la distancia entre las estructuras neurovasculares próximas a los portales y se realizó un análisis estadístico con los resultados. Los resultados del estudio anatómico evidenció que portal antero-medial es el portal más seguro debido a que la distancia de dicho portal a una estructura neurovascular fue la más elevada, obteniendo una media de 11,30 mm±11,25, la menor distancia encontrada fue la del portal postero-medial con una media de 2,84 mm±1,28. El 10 % de los portales laterales resultaron con lesión de estructuras venosas tributarias de la vena safena menor. El portal antero-medial es el portal más seguro pero con mayor variabilidad respecto a las distancias de las estructuras neurovasculares al portal y el portal postero-medial es el de mayor riesgo debido a la mayor presencia de estructuras neurovasculares.

In the last three decades the procedure of ankle arthroscopy has increased in ankle surgery. It is preferred to open surgery for multiple reasons, the most important is that it has fewer complications, with a prevalence of 7.3 % for arthroscopy and 15.9 % for open surgery. Previous studies of ankle arthroscopy reported general complications between 0.9 to 17 % which involved cutaneous nerves at a rate of 33 to 50 %, mainly the superficial peroneal nerve. The principal objective of this study was to determine the neurovascular structures near the arthroscopic portals of the ankle. We carried out anatomical, observational, transversal and descriptive studies. This study was performed with 10 ankles of Mexican population. A 4 mm trocar was introduced in some of the portals described in the literature and superficial dissection of the feet was made. Subsequently, the distance between the nearest neurovascular structures was measured, and statistical analysis of the results was realized. The results of the anatomic study was that the anterior-medial portal was considered the safest portal because it has the highest distance between the portal and the neurovascular structure, with an average of 11.30 mm±11.25, the posterior-medial portal has the smallest average with 2.84 mm±1.28. A lesion of the small saphenous vein was reported in 10 % of the lateral portals. The antero-medial portal is the safest but with highest variability regarding the distances of the neurovascular structures to the portal and the postero-medial portal has the highest risk due to the increased presence of neurovascular structures.